This invention relates in general to electric signal processing circuits and, more particularly, to new and improved means for converting ternary data carried on two transmission lines into binary data for transmission on one line.
Technological advance in the field of signal processing, as exemplified by the development of pulse code modulation, has evolved along several lines. In general, most systems utilize a binary modulation.
There are instances, however, where a ternary signal is convenient. In such a system three conditions may be signalled by means of on and off pulses carried on three wires, with pulse signals carried on one pair of wires, a line, indicating one condition, pulse signals on another pair or line indicating another condition, and the absence of signals, the third condition, for example. Such systems are used in control systems where three levels are used to signal a particular operation or condition: forward, reverse, or neutral; or up, down, or center. Some inertial guidance systems use ternary signals for communicating error signals between the stable platform and computer. In other systems, binary signals are used. It is becoming more and more desirable to arrange for communications between system components which were originally built to use differing systems. In addition there are recognized economies in system cost and improvements in system reliability to be gained by communicating on two wires as compared to three.